This invention relates to electromagnetic devices; and, more particularly, to the use of nanomaterials in insulation coatings for these devices.
Organic resin compositions are used as coatings for the mechanical, electrical and environmental-resistance they impart to electromagnetic devices. The coatings provide a mechanical strength, electrical insulation, and environmental protection for improved long-term durability of the devices, as well as increasing the quality of the final product. Some of these beneficial properties can be improved by the addition of inorganic fillers such as silica, calcium carbonate, alumina, etc. However, a problem with the current state of this technology is that the inorganic materials used in the coatings do not always remain suspended in the mixtures for the coatings during storage of the coating mixtures, resulting in a non-homogeneous coating mixture. When the coating mixtures are applied to the devices to form a coating on the device, areas of weakness result in the coating that, in turn, can cause failure of a device.
This current state of the art raises several issues related to the handling of the coating, its agitation (to produce homogeneity before application) and its pumping, and concerns about the homogeneity of both the applied liquid and the resulting cured film. Prior approaches employed to address these problems have focused on the use of fumed silica and other materials used as suspension agents for the inorganic materials. But, in some instances, use of these agents produce undesirable results because of rheological changes which occur and cause inconsistencies in the applied coatings.